I'm probably worrying about nothing but my baby is nearly five months old and has stopped babbling and cooing. He was doing it loads from three to four months but doesn't do it at all now. He still makes noises like giggling, grunting and, most recently, squealing. He used to love when I'd copy his sounds and do it back to me. His hearing seems fine as he responds to noises and when I call to him. I was trying to remember when it started and it was after his second jabs. Like I say, it's probably nothing but I can't help worrying.